French police will no longer be allowed to call suspects the familiar "tu" (meaning "you"), and will have to address anyone they speak to using the French equivalent of "sir" or "madam".

The document explicitly forbids officers from using the familiar “tu” [“you”, in the singular] form of address to members of the public - in any circumstances.

Instead, anyone they speak to - including youths who would have no compunction in calling them “tu” to their faces - must now be addressed using the formal “vous” [“you” in the plural] at all times.

The new code of conduct states: “Police officers are at the service of the general public. Their relationship with the public must be marked by impeccable courtesy. This excludes the informal ‘tu’.

“Officers are expected to behave in all circumstances in an exemplary fashion and with complete respect for the dignity of individuals. This will inspire greater respect in return.”

‘Tu’ can be insultingly over-familiar

In France, “tu” is normally used among family, friends and close acquaintances, as well as when speaking to young children.

In schools, teachers call their pupils “tu” until they are in their mid-teens, while children are always expected to reply using “vous”.

The inappropriate use of “tu” is considered over-familiar - and sometimes deliberately belittling.

Applying the new code of conduct will be a painful change for certain police units for whom the use of the informal address, especially when dealing with youths in France’s troubled suburbs, is second nature.

“But it carries an implied threat; it’s the kind of thing that can quite naturally ignite a violent reaction and it’s always the youths who come off badly.

“Quite rightly a lot of young people refuse to be spoken to this way.”

Members of the Anti-Criminal Brigade (BAC), a plain-clothes police group that is particularly active in France’s restive suburbs, told France Info that they were worried about the implication of the directive.

One officer, named only as Matthieu, said that using the familiar form of address was “an indispensable tool for asserting authority”.

“This measure is not going to make our lives any easier,” he said. “It certainly won’t alleviate any of the stress of the job. It may even aggravate it.”

His colleague Daniel added that officers were specifically trained as to when it was acceptable to call someone “tu” or “vous”.